A technology of acquiring a three-dimensional image using a capturing device is developing. Depth information (depth map) is required for acquiring a three-dimensional image. Depth information is information that indicates a spatial distance and shows perspective information of a point with respect to another point in a two-dimensional image.
A method in which infrared (IR) structured light is projected to an object and light reflected from the object is interpreted to extract depth information is one of the methods of acquiring depth information. According to the method using the IR structured light, there is a problem in that it is difficult to obtain a desired level of depth resolution for a moving object.
A time-of-flight (TOF) method is gaining attention as a technology for substituting the method using IR structured light. According to the TOF method, a distance from an object is calculated by measuring time of flight, i.e., the time taken for emitted light to be reflected.
Generally, a camera according to the TOF method adjusts the angle of light to scan a front surface of an object. The TOF camera has problems of having low optical efficiency and a large number of operations.